Metal is one of the most widely used materials in the world. One can find metal in small objects from jewelry to large objects like buildings. Metal has various desirable properties and many applications; however, metal is susceptible to oxidation and corrosion (e.g., rust). Under normal conditions, if water and/or or one or more additional oxidizing components (oxygen, CO2, SO2, H2S, Cl−, etc) are present in the environment, such components react with various metals to produce rust or various other corrosion by-products. This is especially true in high-temperature and high-humidity environments where metal in these environments is more quickly corroded. Therefore, it is important to prevent metal components from succumbing to environmental corrosion.
Generally there are two ways to protect metal components from corrosion. They are permanent rust prevention and temporary rust prevention where permanent rust prevention uses metal coatings, such as zinc-plating and chrome-plating, and/or polymer coatings, such as paints. On the other hand, temporary rust prevention utilizes oil coatings and/or wax-based coating, or tries to improve various environmental conditions by using drying agents or protective liners such as aluminum foil. In temporary rust prevention, the coating can separate the surface of metal from air and water to prevent it from being corroded by rust. However, this solution loses efficacy due to the oxidation of the antirust oil/wax itself and/or it takes a lot of time and energy to remove this coating. Additionally such coatings tend to be harmful to environmental. Drying agents generally are cost prohibitive and the amount of such compounds needs to be calculated precisely. Also, in some applications, drying agents must be hermitically sealed and are therefore inconvenient for import-export customs inspection. Another drawback to drying agents is that they easily absorb moisture in the air and reach their saturation point in a short time thereby necessitating replacement.
Recently another corrosion protection technology has emerged, this being volatile, or vapor phase, corrosion inhibitors (VCIs). One application of these materials is to add one or more VCIs into traditional packing materials. VCIs function due to the fact that volatile, or vapor phase, corrosion inhibitor volatilizes into a gas, or vapor, and this gas, or vapor, is transferred to the surface of the item/article/surface to be protected by condensation of the VCI's vapor on the surface of the item, article, and/or surface to be protected.
In the marketplace, there are products that contain one or more volatile corrosion inhibitors in a paper, or plastic, sheet. Such products are then used to wrap metal objects to protect such objects from corrosion. However, such products suffer from various drawbacks. For example, paper wrappings cannot be adhered hermitically onto the surface of a metal object thereby resulting in a gap between the paper and metal object. As such, paper-based VCI wrappings cannot completely prevent the oxygen and moisture in the air from reaching the surface of a metal object. Furthermore, such paper wrapping generally needs to be attached, or adhered, to a metal object with tape. This takes a significant amount of time and effort to accomplish and only offers a modest amount of additional protection in situations where the paper wrapper becomes wet or rips.
Thus there is a need in the art for a solution to various corrosion issues where VCI-containing paper and polymer films, or wrappings, do not alone offer adequate protection.